[MNG-7771] Don't use ArtifactResolutionException#getMessage() w/o knowing whether there are other exceptions or not

**[Michael Osipov](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=michael-o)** opened **[MNG-7771](https://issues.apache.org/jira/browse/MNG-7771?redirect=false)** and commented

`ArtifactResolutionException#getMessage()` only considers the message from the first cause, completely ignoring other causes. So it is order-dependent and can be misleading. Create an expeception-agnotic message and all submessages shall be retrieved through API.

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**Affects:** 3.8.8, 3.9.1, 4.0.0-alpha-5

This issue is a sub-task of [MNG-7770](https://issues.apache.org/jira/browse/MNG-7770)

**Backported to:** [4.0.x-candidate](https://github.com/apache/maven/milestone/115?closed=1), [3.9.x-candidate](https://github.com/apache/maven/milestone/112?closed=1)